No, not really. If you have a side project making $1MM ARR, no one is going to yell at you for misnaming it.
Once you make enough money to sustain yourself. Hopefully this will come in the near future :D
I'd agree with others that it means you're able to make a living off of it or you can hire people and start building out the team.
That makes every one of [email protected] a startup before I write a single line of code
When you start selling and put regular, consistent effort into growth. By that definitely Spell Tracker was a startup from halfway though my paternity leave with my first child until I quit Google and started building something bigger.